The present invention refers to a hub-bearing unit for a wheel of a motor vehicle, in particular a utility vehicle, the unit comprising a radially outer annular hub adapted for connection to the wheel of a vehicle, and having a central axial cylindrical seat for a bearing, and a bearing having a radially outer rotating ring mounted in the cylindrical axial seat for rotating fast with the annular hub.
A hub-bearing unit of the above-indicated kind is shown schematically in FIG. 1. With reference to FIG. 1, numeral 10 indicates a radially outer annular hub of steel, forming a radially outer flange 11 with axial holes 12 for connecting the hub to a wheel 14 of a motor vehicle by means of studs 13. The hub has a central axial cylindrical seat 15 in which there is mounted a bearing of the so-called first generation, indicated overall 16. The bearing 16 comprises a stationary radially inner ring 17, a rotating radially outer ring 18, and rolling bodies 19, in this case tapered rollers, radially interposed between the inner 17 and outer 18 rings. The inner stationary ring 17 is locked on a central axle 20 for supporting the wheel; the outer rotating ring 18 is mounted in the cylindrical seat 15 of the hub so as to rotate integral therewith.
According to prior art, the bearing 14 is axially locked in the cylindrical seat 15 of the annular hub by means of a shoulder 10a formed on the outboard side of the hub, and on the inboard opposite side by other locking means, usually consisting of a ring nut or a seeger ring, cooperating with a circumferential groove formed in the hub, or, as in the example of FIG. 1, in a flange of the brake rotor. The outer ring 18 of the bearing is rotationally locked in the cylindrical seat 15 of the hub by a forced coupling with radial interference.